The Importance of Permafrost Thaw, Fire and Logging Disturbances as Driving Factors of Historical and Projected Carbon Dynamics in Alaskan Ecosystems

Friday, 19 December 2014: 2:40 PM
Helene Genet1, Yujin Zhang2, Anthony David McGuire3, Yujie He4, Kristofer D Johnson5, David V D'Amore6, Xiaoping Zhou7, Alec Bennett8, Amy Lynn Breen8, Frances Biles6, Norman B Bliss9, Eugenie Susanne Euskirchen1, Thomas A Kurkowski8, Neal Pastick10, Scott T Rupp8, Bruce K Wylie11, Zhiliang Zhu12 and Qianlai Zhuang13, (1)University of Alaska Fairbanks, Fairbanks, AK, United States, (2)Institute of Arctic Biology, University of Alaska, Fairbanks, Fairbanks, AK, United States, (3)University of Alaska Fairbanks, Institute of Arctic Biology, Fairbanks, AK, United States, (4)Purdue University, Department of Earth, Atmospheric and Planetary Sciences, West Lafayette, IN, United States, (5)U.S. Forest Service, Newtown Square, PA, United States, (6)U.S. Forest Service, Juneau, AK, United States, (7)U.S. Forest Service, Portland, OR, United States, (8)University of Alaska Fairbanks, Scenarios Network for Alaska & Arctic Planning, Fairbanks, AK, United States, (9)ASRC InuTeq, Sioux Falls, SD, United States, (10)Stinger Ghaffarian Technologies Sioux Falls, Sioux Falls, SD, United States, (11)USGS, Baltimore, MD, United States, (12)USGS, Reston, VA, United States, (13)Purdue University, West Lafayette, IN, United States
Carbon dynamics of natural ecosystems are influenced by disturbance regimes of various frequencies and magnitudes. With global change, these disturbances are projected to increase in frequency and/or magnitude and may have significant effects on future net carbon balance, especially in high latitude ecosystems where carbon stocks are among the largest on Earth and climate change is substantial. In Alaska, permafrost degradation and fire in the boreal and arctic regions and logging in the southern coastal region are the main disturbances that affect ecosystems. Large uncertainties related to the effects of these disturbances on the capacity of these regions to store carbon still exist mainly due to difficulty in representing permafrost degradation in current ecosystem models. We ran the Terrestrial Ecosystem Model (TEM), which explicitly simulates the carbon cycle and permafrost dynamics, coupled with a disturbance model (the Alaska Frame Based Ecosystem Code, ALFRESCO) to assess the relative importance of permafrost thaw, wildfire, and forest management on historical and projected carbon balance and carbon stocks in Alaska, from 1950 to 2100, at a 1-km resolution. Our simulations showed that the increase in plant productivity in response to warming in boreal and arctic regions is offset by soil carbon loss due to permafrost degradation and wildfire combustion during both historical and future simulations. Fire disturbances act as a catalyst accelerating permafrost degradation and associated soil carbon loss. In addition, our preliminary results for south coastal regions of Alaska indicate that logging of second growth forests could influence carbon dynamics in that region. Overall, these results have implications for land management strategies and illustrate the importance of taking into account multiple types of disturbance regimes in ecosystem models for Alaska.